Mattress construction including stitch-bonded flame barrier having stretch and recovery character

ABSTRACT

A mattress construction having a resilient core incorporating deformable foam either alone or in combination with integrated springs with a complimentary flame barrier fabric disposed in overlying relation to the resilient core. The flame barrier fabric has a stitch-bonded construction with elastomeric yarns extending in stitched relation through a fleece substrate of substantially inelastic character incorporating a percentage of flame retardant fibers. In a relaxed condition, the fleece substrate is bunched between stitch lines formed by the elastomeric yarns. Upon the application of tension, the barrier fabric stretches by the extension of the elastomeric stitching yarns in combination with a flattening of the fleece substrate.

TECHNICAL FIELD

This non-provisional application claims the benefit of, and priorityfrom, U.S. provisional application 61/404,694 having a filing date ofOct. 7, 2010. The contents of such provisional application and allpatent documents referenced herein are hereby incorporated by referencein their entirety as if fully set forth herein.

TECHNICAL FIELD

The present invention relates generally to residential and commercialmattresses and more particularly to mattresses incorporating one or moreflame barrier panels disposed in overlying relation to a resilient foamcore.

BACKGROUND OF THE INVENTION

It is known to provide mattresses with so called “flame barrier”materials positioned between a resilient mattress core and a decorativetextile covering. In one approach, prior flame barrier materials havebeen formed from non-woven materials of fleece constructionincorporating inherently flame retardant fiber constituents. While suchconstructions provide good flame blocking and insulation character, theyhave limited capacity to stretch and recover. This limitation may beparticularly problematic with respect to mattresses which incorporatematerials such as visco-elastic foam and the like which may be requiredto undergo substantial localized deformation.

In order to address the desire for stretch and recovery to match theunderlying foam core materials, the industry has turned to the use ofcircular knitted products using filament and spun yarns. Such circularknit constructions may be formed from fibers having inherent flameresistance and/or may be treated with chemical compositions to provideenhanced flammability resistance. While circular knit structures tend tohave good stretch and recovery character, their construction is suchthat when they are in a stretched condition interstices between theyarns open up. Under these conditions, the coverage of the underlyingmattress core may be diminished. This reduced coverage thus reduces theinsulating character of the barrier fabric in the tensioned state.

In light of the above deficiencies in the known art there is acontinuing need for a mattress incorporating a flame barrier layer whichhas substantial stretch and recovery corresponding to an underlying coreincorporating a deforming foam or other material either alone or incombination with integrated springs while providing continuous coverageover the full range of stretch.

SUMMARY OF THE INVENTION

The present invention provides advantages and alternatives over theprior art by providing a stretchable flame barrier material and moreparticularly, a mattress construction having a resilient coreincorporating deformable foam either alone or in combination withintegrated springs with a complimentary flame barrier fabric disposed inoverlying relation to the resilient core. The flame barrier fabric has astitch-bonded construction with elastomeric yarns extending in stitchedrelation through a fleece substrate of substantially inelastic characterincorporating a percentage of flame retardant fibers. In a relaxedcondition, the fleece substrate is bunched between stitch lines formedby the elastomeric yarns. Upon the application of tension, the barrierfabric stretches by the extension of the elastomeric stitching yarns incombination with a spreading (i.e. flattening) of the fleece substrate.This configuration provides continuous coverage over the full range ofstretch. The barrier fabric may incorporate a substantially inelasticselvage to aid in processing and formation without curling.

Other exemplary aspects of the invention will become apparent uponreview of the following detailed description of preferred embodimentsand practices.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in, and whichconstitute a part of this specification, illustrate exemplaryconstructions and procedures in accordance with the present inventionand, together with the general description of the invention given aboveand the detailed description set forth below, serve to explain theprinciples of the invention wherein:

FIG. 1 is a partial cut-away view of an exemplary mattress construction;

FIG. 2 is a cross-sectional view of the exemplary mattress constructionof FIG. 1;

FIG. 3 is a needle point diagram illustrating a stitch formingarrangement for an exemplary flame barrier fabric for use in overlyingrelation to a resilient core in a mattress;

FIG. 4 is a schematic view illustrating an exemplary stitch-bondingoperation;

FIG. 5 is a schematic view illustrating the arrangement of yarns in theexemplary flame barrier fabric of FIG. 3 in relaxed condition; and

FIG. 6 is a schematic view illustrating the arrangement of yarns in theexemplary flame barrier fabric of FIG. 3 in stretched condition.

While the invention has been illustrated and generally described aboveand will hereinafter be described in connection with certain potentiallypreferred embodiments and practices, it is to be understood that in noevent is the invention limited to such illustrated and describedembodiments and practices. On the contrary, it is intended that thepresent invention shall extend to all alternatives and modifications asmay embrace the general principles of this invention within the full andtrue spirit and scope thereof. Also, it is to be understood that thephraseology and terminology used herein are for purposes of descriptiononly and should not be regarded as limiting. The use herein of termssuch as “including” and “comprising” and variations thereof is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items and equivalents thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Reference will now be made to the drawings, wherein to the extentpossible like reference numerals are utilized to designate correspondingcomponents throughout the various views. In FIG. 1 there is illustrateda mattress and box spring set 10 including a mattress 12 and anunderlying supporting box spring 14. As will be appreciated, themattress 12 may be used with or without the box spring 14. In theexemplary construction, the mattress 12 generally includes a core 16 offoam alone or in combination with supporting springs 18 (FIG. 2). By wayof example only, and not limitation, the foam may be a visco-elasticpolyurethane foam or the like having a density of about 1-12 pounds percubic foot and more preferably about 3 to 7 pounds per cubic footalthough other resilient foams and densities may likewise be utilized.The foam core 16 may have a continuous stiffness throughout thethickness of the mattress 12 or may be layered with varying stiffnesslevels at different positions in the thickness dimension.

In the illustrated arrangement, the core 16 is at least partiallycovered with an overlay structure 20 (FIG. 2). As illustrated, theoverlay structure 20 includes at least one layer of a flame barrierfabric 30 of stitch-bonded construction. A covering layer 32 ofdecorative fabric or the like may be disposed in overlying relation tothe flame barrier fabric 30. As will be appreciated, while the flamebarrier fabric 30 is illustrated as being in direct contact with boththe core 16 and the covering layer 32, it is likewise contemplated thatone or more intermediate layers may be interposed between the flamebarrier fabric 30 and the core 16 and/or between the flame barrierfabric 30 and the covering layer 32.

If desired, the flame barrier fabric 30 may be adjoined to the coveringlayer 32. Such connection may be at intermediate discreet positions, ormay be along a substantially continuous interface. By way of exampleonly, such connection may be made by quilting, adhesive bonding or othertechniques as may be known to those of skill in the art.

As noted previously, the flame barrier fabric 30 is of a stitch-bondedconstruction. In such a construction yarns are stitched in parallel rowsthrough a substrate material to define a coordinated structure. Thestitches are formed at needles disposed across the width of thestitch-bonding machine. The stitching yarns may be shifted betweenneedles to yield a desired pattern of yarn segments extending betweenstitch positions. By way of example only, an exemplary stitch-bondingoperation is illustrated and described in U.S. Pat. No. 6,655,392 toWildeman et al. the contents of which are incorporated herein byreference.

By way of example only, and not limitation, one exemplary constructionfor the flame barrier fabric 30 is illustrated in FIG. 3. As shown inFIG. 3 the exemplary flame barrier fabric 30 uses elastomeric stitchingyarns 38 to form a stretch zone 40 of substantial width so as tosubstantially cover at least one side of the mattress 12. According toone exemplary practice, the elastomeric stitching yarn 38 may be a 140denier SPANDEX yarn wrapped with a 150 denier, air entangled texturedpolyester yarn of substantially non-stretchable character. However, itis contemplated that any number of other wrapped or unwrappedelastomeric yarns may be used. By way of example only, alternativeelastomeric components such as LYCRA®, HYTREL®, or the like may besubstituted for SPANDEX. Likewise, varying deniers may be used for anyof the yarn components. It is also contemplated that the wrapping yarnmay be a material such as high stretch polyester, cold drawn flatpolyester or the like.

By way of example only, one method contemplated for formation of a flamebarrier fabric 30 in accordance with the present invention involves a socalled two-bar stitch-bonding procedure shown schematically in FIG. 4.In the illustrated exemplary practice, one or more plies of a fleecesubstrate material 50 of fibrous nonwoven construction is conveyed to astitch-forming position in the direction indicated by the arrow. As willbe appreciated, while FIG. 4 illustrates the use of a single ply ofsubstrate material 50, it is also contemplated that multiple plies maybe used if desired.

During the stitch-bonding process a plurality of needles 54 (shown ingreatly exaggerated dimension) pierce the substrate material 50 andengage elastomeric stitching yarns 38 delivered into position by theyarn guides of the front bar such that the stitching yarns are capturedwithin a hook portion of the needles 54 (only one shown). The substratematerial 50 may be held down by finger elements 56 (only one shown) topromote stability. In this regard, while only a single finger element 56is shown, in actual practice a multiplicity of such elements may bepositioned in adjacent relation across the width of the stitching zone.As the needle 54 is reciprocated downwardly, a closing element such as aclosing wire which moves relative to the needle 54 closes the hookportion to hold the stitching yarns therein. With the hook portionclosed, the captured stitching yarn is pulled through the interior of animmediately preceding yarn loop disposed around the shank of the needle54 at a position below the substrate material 50. As the capturedstitching yarn is pulled through the interior of the preceding yarnloop, a stitch is formed which is knocked off of the needle 54. As theneedle 34 is raised back through the substrate material 50, the hookportion is reopened and a new yarn loop moves out of the hook portionand is held around the shank of the needle 54 for acceptance of the yarnand formation of a subsequent stitch during the next down stroke. Aswill be appreciated, while only a single elastomeric stitching yarn 38and needle 54 are shown, a large number of such yarns and needles arearranged for interaction across the width of the stitch-bondingapparatus. Thus, during the formation process, elastomeric stitchingyarns 38 may be shifted back and forth laterally between defined needlesto simultaneously form a multiplicity of zigzag stitch lines extendingin the machine direction across the width of the stretch zone 40 asshown in FIG. 3.

According to one exemplary practice, the substrate material 50 is formedfrom a blend of short staple fibers. The substrate material 50 may besubjected to carding or other stability enhancing procedures prior tostitching if desired. Typically, the fibers will have a length of about6 inches or less although other lengths may be used. In one exemplarypractice, the substrate material is made up of about 30% to about 100%silica rayon fibers in which flame retardant properties are enhanced byembedding silica in the cellulosic fiber (also known as FR Rayon or FRViscose) or other self charring fibers and optionally about 5% to about65% polyester fibers and optionally about 5% to about 25% para-aramid ormeta-aramid fibers wherein all percentages are by weight. Onepotentially desirable blend includes 60% silica rayon fibers, 30%polyester staple fibers and 10% para-aramid staple fibers. Anotherpotentially desirable substrate material is 100% silica rayon. Thesubstrate material 50 preferably has a mass per unit area of about 80 toabout 200 grams per square meter although higher or lower levels may beused. A mass per unit area of about 140 grams per square meter may beparticularly desirable for some applications.

According to one contemplated practice, the elastomeric stitching yarns38 may be stitched on a stitch-bonding machine at a 14 gauge setting(i.e. 14 needles per inch). In one exemplary practice, the elastomericstitching yarns being partially threaded in a 1 miss 2 (1 in 2 out)manner as illustrated. Thus, every third needle engages an elastomericstitching yarn 38. Of course, the unused needles may be removed andother threading arrangements may be used if desired. As illustrated, inthe exemplary embodiment using this stitch notation the elastomericstitching yarns 38 are stitched as flat stitches in a zigzag patternbetween needle lines according to a stitch notation of 1-0, 3-4 therebyproviding a relatively long transverse diagonal float segment betweenstitch points. As will be appreciated, the stitching is done with theyarns 38 in a stretched state. A stretched diagonal float distancebetween stitch points of about 0.20 cm or greater may be desirable. Astretched diagonal float distance of about 0.25 cm to about 5 cm orgreater, and more preferably, about 0.4 cm to about 2.5 cm may bedesirable in some environments of use. In this regard, the presence ofsubstantial extendable length float segments is believed to promoteelasticity in the final product in both the machine and cross-machinedirection. Of course, other stitch notations may be used if desired.

The final fabric finished weight will normally be in the range of about2 to 20 ounces per square yard. A finished weight in the range of about6 to 12 ounces per square yard and more preferably about 9 ounces persquare yard may be particularly desirable in some environments of use.Of course, other fabric weights may be used if desired.

As illustrated, in the exemplary construction the barrier fabric 30 alsoincludes a pair of lateral selvage zones 60 which are substantiallyinelastic in character. In practice, the selvage zones 60 may be formedby stitching inelastic yarns 62 delivered from the yarn guides of theback bar in a pattern which limits stretch. By way of example only, theinelastic yarns 62 may be polyester yarns such as a 150 denier, 34filament polyester flat yarn stitched in a chain stitch at a notation of1,0/0,1 or the like. As shown, the inelastic yarns may be partiallythreaded such that every needle in the selvage zones is not engaged. Inone exemplary practice, the inelastic stitching yarns being partiallythreaded in a 1 miss 2 (1 in 2 out) manner as illustrated. Thus, withinthe selvage zones, every third needle engages an inelastic elastomericstitching yarn 62. Of course, the unused needles may be removed ifdesired and other threading arrangements may be used if desired.

In practice, the selvage zones 60 may have a relatively narrow width ofabout 1 to about 5 inches. By way of example only, a selvage width ofabout 3 inches on each side may be desirable in some environments ofuse. However, other widths may be used if desired. As will beappreciated, the presence of the substantially stretch-free selvagezones 60 provides dimensional stability to the overall structure duringfinishing and processing.

As indicated previously, the flame barrier fabric 30 may stretchsubstantially through the stretch zone by extension of the elastomericstitching yarns 38 in combination with a spreading (i.e. flattening) ofthe fleece substrate. This behavior is best understood through jointreference to FIGS. 5 and 6. As shown, in the relaxed state (FIG. 5) thestitching yarns contract from their as-stitched condition and thesubstrate material 50 is bunched between stitch points of theelastomeric stitching yarns 38 on one side of the flame barrier fabric30. This bunching defines an undulating pattern of parallel raised rowsof the fleece substrate 50 extending in the machine direction of thefabric between the stitch points.

As illustrated in FIG. 6, upon the application of a tensioning force inthe cross machine direction, the elastomeric stitching yarns 38 stretchand the rows of substrate material 50 flatten out. In this stretchedcondition the substrate material 50 continues to provide continuouscoverage. Thus, the stretch zone 40 may be extended significantlywithout opening voids in coverage. Upon application of localizedtensioning force in the machine direction, stretch may take place as thestitch lines are pulled towards one another and the crossing floatsegments of the elastomeric stitching yarns 38 are urged towardsalignment with the machine direction. Without being limited to aspecific theory, it is believed that the longer float segments formed bycausing the elastomeric yarn to skip two or more needles between stitchpoints may facilitate stretching in the machine direction by permittingmaterial contract laterally as it is extended longitudinally.

Due to the elastomeric nature of the stitching yarns 38, when tensioningforces are relieved, the flame barrier fabric reverts back to its lowenergy state (FIG. 5). Accordingly, the flame barrier fabric 30 exhibitssubstantial stretch and recovery character so as to conform todimensional changes in the foam core 16. By way of example only, and notlimitation, the exemplary material within the stretch zone 40 of a flamebarrier fabric 30 formed as described herein may be stretched up to atleast 50% (i.e. to 150% of its initial dimension) and more preferably upto 75% (i.e. to 175% of its initial dimension) in each of the machinedirection and the cross-machine direction and thereafter recover towithin 5 percent of its initial unstrained dimensions upon removal ofthe deforming force. Such elastomeric stretch and recovery characterfacilitates localized deformation for the foam core 16. Moreover, theexemplary material within the stretch zone 40 of a flame barrier fabric30 formed as described herein may be characterized by a relatively lowmodulus of elasticity which is preferably lower than the compressivemodulus of the foam core 16. Thus, upon application of a compressiveforce to the surface of the mattress, 12, the foam core 16 will providegreater resistance to deformation than the flame barrier fabric. Thefoam core 16 thereby substantially controls the level of supportprovided to a user while the flame barrier fabric 30 follows thedimensional changes in the foam core 16.

By way of example only, and not limitation, in both the machinedirection and the cross-machine direction, the stretch zone 40 ispreferably characterized by 50 percent elongation at less than about 500grams applied force per centimeter width and more preferably by 50percent elongation at less than about 300 grams applied force percentimeter width. That is, a 1 cm width of the material forming thestretch zone 40 may require no more than 500 grams applied stretchingforce (and more preferably no more than 300 grams applied stretchingforce) in order to stretch to 150% of its initial length.

In practice, the stretch zone of the flame barrier fabric 30 provides aneffective insulating flame barrier across the foam core 16 in all stagesof deformation since the substrate material 50 provides continuouscoverage. Moreover, the fiber blend in the substrate material is highlyeffective in curtailing any flame propagation despite the presence ofperforations formed during the stitch-bonding formation procedure.Specifically, upon exposure to a flame, the silica rayon fibers (orother FR constituent) forms a flame-blocking char which provides astable flame barrier.

It is to be understood that while the present invention has beenillustrated and described in relation to certain potentially preferredembodiments, constructions and procedures, that such embodiments,constructions and procedures are illustrative only and that the presentinvention is in no event to be limited thereto. Rather, it iscontemplated that modifications and variations embodying the principlesof this invention will no doubt occur to those of skill in the art. Itis therefore contemplated and intended that the present invention shallextend to all such modifications and variations as may incorporate thebroad aspects of the invention within the full spirit and scope thereof.

1. A mattress construction comprising: a deformable foam core comprisinga foam having a density in the range of about 1 to 12 pounds per cubicfoot; and a flame blocking overlay structure disposed at least partiallyaround the foam core, wherein the overlay structure comprises at leastone layer of flame barrier fabric of stitch-bonded construction having amachine direction and a cross-machine direction, the flame barrierfabric including an inelastic nonwoven fibrous substrate materialincluding at least 30% by weight flame retardant fiber with a pluralityof elastomeric yarns stitched through the fibrous substrate material,the elastomeric yarns defining a plurality of zigzag stitch linesextending in the machine direction of the flame barrier fabric, whereinthe stitch lines include diagonal float segments extending betweenstitch points, wherein in an unstretched state, the fibrous substratematerial is bunched in an undulating pattern defining a plurality ofraised profile rows extending in the machine direction across one sideof the flame barrier fabric, and wherein upon application of astretching force, the flame barrier fabric is stretchable by at least50% in each of the machine direction and cross-machine directionfollowed by elastic recovery to within 5% of the unstretched state uponremoval of the stretching force.
 2. The mattress construction as recitedin claim 1, wherein the foam is visco-elastic polyurethane foam.
 3. Themattress construction as recited in claim 2, wherein the foam has adensity in the range of 3 to 7 pounds per cubic foot.
 4. The mattressconstruction as recited in claim 1, wherein the foam surrounds internalsprings.
 5. The mattress construction as recited in claim 1, wherein theelastomeric yarns are wrapped yarns comprising an elastomeric corewrapped with inelastic textured yarn.
 6. The mattress construction asrecited in claim 1, wherein the nonwoven fibrous substrate material hasa mass per unit area of about 80 to about 200 grams per square meter. 7.The mattress construction as recited in claim 1, wherein the nonwovenfibrous substrate comprises 30% to 100% silica rayon fibers andoptionally about 5% to 65% polyester fibers and optionally about 5% to25% para-aramid or meta-aramid fibers.
 8. The mattress construction asrecited in claim 1, wherein the nonwoven fibrous substrate comprisessubstantially 100% silica rayon fibers.
 9. The mattress construction asrecited in claim 1, wherein the flame barrier fabric is stretchable byat least 75% in each of the machine direction and cross-machinedirection followed by elastic recovery to within 5% of the unstretchedstate upon removal of the stretching force.
 10. The mattressconstruction as recited in claim 1, wherein a stretch zone of the flamebarrier fabric is characterized by a modulus of elasticity in both themachine direction and the cross-machine direction such that 50 percentelongation requires less than 500 grams applied force per centimeterwidth.
 11. The mattress construction as recited in claim 1, wherein astretch zone of the flame barrier fabric is characterized by a modulusof elasticity in both the machine direction and the cross-machinedirection such that 50 percent elongation requires less than 300 gramsapplied force per centimeter width.
 12. The mattress construction asrecited in claim 1, wherein the overlay structure includes coveringlayer of decorative fabric disposed in overlying relation to the flamebarrier fabric.
 13. A mattress construction comprising: a deformablefoam core comprising a visco-elastic polyurethane foam having a densityin the range of about 3 to 7 pounds per cubic foot; and a flame blockingoverlay structure disposed at least partially around the foam core,wherein the overlay structure comprises a decorative outer fabricoverlying at least one layer of flame barrier fabric of stitch-bondedconstruction having a machine direction and a cross-machine direction,the flame barrier fabric including an inelastic nonwoven fibroussubstrate material including at least 30% by weight of carded silicarayon fiber with a plurality of elastomeric yarns stitched through thefibrous substrate material, the elastomeric yarns defining a pluralityof zigzag stitch lines extending in the machine direction of the flamebarrier fabric, wherein the stitch lines include diagonal float segmentsextending between stitch points at spaced-apart parallel needle lines,wherein in an unstretched state, the fibrous substrate material isbunched in an undulating pattern defining a plurality of raised profilerows extending in the machine direction across one side of the flamebarrier fabric, and wherein upon application of a stretching force, theflame barrier fabric is stretchable by at least 50% in each of themachine direction and cross-machine direction followed by elasticrecovery to within 5% of the unstretched state upon removal of thestretching force.
 14. The mattress construction as recited in claim 13,wherein the foam surrounds internal springs.
 15. The mattressconstruction as recited in claim 13, wherein the elastomeric yarns arewrapped yarns comprising an elastomeric core wrapped with inelastictextured yarn.
 16. The mattress construction as recited in claim 13,wherein the nonwoven fibrous substrate material has a mass per unit areaof about 80 to about 200 grams per square meter.
 17. The mattressconstruction as recited in claim 13, wherein the nonwoven fibroussubstrate comprises 30% to 100% silica rayon fibers and optionally about5% to 65% polyester fibers and optionally about 5% to 25% para-aramid ormeta-aramid fibers.
 18. The mattress construction as recited in claim 1,wherein the nonwoven fibrous substrate comprises substantially 100%silica rayon fibers.
 19. The mattress construction as recited in claim1, wherein a stretch zone of the flame barrier fabric is characterizedby a modulus of elasticity in both the machine direction and thecross-machine direction such that 50 percent elongation requires lessthan 500 grams applied force per centimeter width.
 20. A mattressconstruction comprising: a deformable foam core comprising foam having adensity in the range of about 3 to 7 pounds per cubic foot; and a flameblocking overlay structure disposed at least partially around the foamcore, wherein the overlay structure comprises a decorative outer fabricoverlying at least one layer of flame barrier fabric of stitch-bondedconstruction having a machine direction and a cross-machine direction,the flame barrier fabric including an inelastic nonwoven fibroussubstrate material including at least 30% by weight of flame retardantcellulosic fiber with a plurality of elastomeric yarns stitched throughthe fibrous substrate material, the elastomeric yarns defining aplurality of zigzag stitch lines extending in the machine direction ofthe flame barrier fabric, wherein the stitch lines include diagonalfloat segments extending between stitch points at spaced-apart parallelneedle lines, wherein in an unstretched state, the fibrous substratematerial is bunched in an undulating pattern defining a plurality ofraised profile rows extending in the machine direction across one sideof the flame barrier fabric, and wherein upon application of astretching force, the flame barrier fabric is stretchable by at least50% in each of the machine direction and cross-machine directionfollowed by elastic recovery to within 5% of the unstretched state uponremoval of the stretching force, and wherein a stretch zone of the flamebarrier fabric is characterized by a modulus of elasticity in both themachine direction and the cross-machine direction such that 50 percentelongation requires less than 300 grams applied force per centimeterwidth.